Preparation assistance for Linux Device Driver. This doesn't fully provide the in and out of LDD3 book. Rather it advices outline for studying Linux Device Driver. It will be updated in the course of time if required.
Device drivers provide an interface between operating systems and hardware devices. They are split into character, block, and network modules. Character drivers handle streams of bytes like files and implement open, close, read, and write functions. Block drivers are similar but differ in how the kernel manages data internally. Network drivers send and receive data supervised by the device subsystem. Device drivers provide mechanisms and not policies, and security is enforced by kernel code to avoid encoding policies directly into drivers. Loadable modules can add functionality while the system is running.
Multiprocessors(performance and synchronization issues)Gaurav Dalvi
This document discusses performance and synchronization issues in multiprocessor systems. It describes shared memory architectures like UMA, NUMA and distributed shared memory. It discusses factors that affect cache performance like CPU count, cache size and block size. It also discusses synchronization mechanisms like locks, flags and barriers that are used to synchronize access to shared resources. Different hardware primitives for synchronization are described, including atomic exchange, test-and-set, and load-linked/store-conditional instructions.
Cache coherence problem and its solutionsMajid Saleem
This document discusses cache coherence in shared memory multiprocessor systems. It defines cache coherence as ensuring changes to shared memory values are propagated throughout the system quickly. It describes two main approaches to maintaining cache coherence - software-based and hardware-based solutions. Hardware-based approaches can use either snooping or directory-based protocols. Snooping is used in low-end multiprocessors and involves broadcasting cache coherency messages on a shared bus. Directory-based protocols are used in higher-end systems and involve tracking the state of cached blocks in a directory.
IT IS ABOUT MULTIPROCESSING,COMMUNICATION BETWEEN THE PROCESS THROUGH MESSAGE PASSING AND SHARED MEMORY.SYNCHRONIZATION MECHANISM AND SYNCHRONIZATION USING SEMAPHORE
The document discusses non-uniform cache architectures (NUCA), cache coherence, and different implementations of directories in multicore systems. It describes NUCA designs that map data to banks based on distance from the controller to exploit non-uniform access times. Cache coherence is maintained using directory-based protocols that track copies of cache blocks. Directories can be implemented off-chip in DRAM or on-chip using duplicate tag stores or distributing the directory among cache banks. Examples of systems like SGI Origin2000 and Tilera Tile64 that use these techniques are also outlined.
The document discusses the advance operating system and describes a microkernel. It notes that a microkernel manages system resources but keeps user and kernel services in separate address spaces to reduce kernel size. This allows the kernel to function better as a small, isolated module. Key advantages are that the system can be more easily expanded by adding applications without modifying the kernel, and modules can be replaced or modified without touching the kernel.
Multithreading allows an operating system to execute multiple tasks simultaneously by using threads. It improves responsiveness, enables resource sharing, and improves scalability. There are three main multithreading models: many-to-one maps many user threads to a single kernel thread; one-to-one uses a one-to-one mapping; many-to-many multiplexes user threads to kernel threads, combining advantages of the other models.
This document discusses multithreading and the differences between tasks and threads. It explains that operating systems manage each application as a separate task, and when an application initiates an I/O request it creates a thread. Multithreading allows a single process to support multiple concurrent execution paths. Benefits of threads include less overhead for creation, termination, and context switching compared to processes. The document concludes that threads enhance efficiency by sharing resources within a process.
Device drivers provide an interface between operating systems and hardware devices. They are split into character, block, and network modules. Character drivers handle streams of bytes like files and implement open, close, read, and write functions. Block drivers are similar but differ in how the kernel manages data internally. Network drivers send and receive data supervised by the device subsystem. Device drivers provide mechanisms and not policies, and security is enforced by kernel code to avoid encoding policies directly into drivers. Loadable modules can add functionality while the system is running.
Multiprocessors(performance and synchronization issues)Gaurav Dalvi
This document discusses performance and synchronization issues in multiprocessor systems. It describes shared memory architectures like UMA, NUMA and distributed shared memory. It discusses factors that affect cache performance like CPU count, cache size and block size. It also discusses synchronization mechanisms like locks, flags and barriers that are used to synchronize access to shared resources. Different hardware primitives for synchronization are described, including atomic exchange, test-and-set, and load-linked/store-conditional instructions.
Cache coherence problem and its solutionsMajid Saleem
This document discusses cache coherence in shared memory multiprocessor systems. It defines cache coherence as ensuring changes to shared memory values are propagated throughout the system quickly. It describes two main approaches to maintaining cache coherence - software-based and hardware-based solutions. Hardware-based approaches can use either snooping or directory-based protocols. Snooping is used in low-end multiprocessors and involves broadcasting cache coherency messages on a shared bus. Directory-based protocols are used in higher-end systems and involve tracking the state of cached blocks in a directory.
IT IS ABOUT MULTIPROCESSING,COMMUNICATION BETWEEN THE PROCESS THROUGH MESSAGE PASSING AND SHARED MEMORY.SYNCHRONIZATION MECHANISM AND SYNCHRONIZATION USING SEMAPHORE
The document discusses non-uniform cache architectures (NUCA), cache coherence, and different implementations of directories in multicore systems. It describes NUCA designs that map data to banks based on distance from the controller to exploit non-uniform access times. Cache coherence is maintained using directory-based protocols that track copies of cache blocks. Directories can be implemented off-chip in DRAM or on-chip using duplicate tag stores or distributing the directory among cache banks. Examples of systems like SGI Origin2000 and Tilera Tile64 that use these techniques are also outlined.
The document discusses the advance operating system and describes a microkernel. It notes that a microkernel manages system resources but keeps user and kernel services in separate address spaces to reduce kernel size. This allows the kernel to function better as a small, isolated module. Key advantages are that the system can be more easily expanded by adding applications without modifying the kernel, and modules can be replaced or modified without touching the kernel.
Multithreading allows an operating system to execute multiple tasks simultaneously by using threads. It improves responsiveness, enables resource sharing, and improves scalability. There are three main multithreading models: many-to-one maps many user threads to a single kernel thread; one-to-one uses a one-to-one mapping; many-to-many multiplexes user threads to kernel threads, combining advantages of the other models.
This document discusses multithreading and the differences between tasks and threads. It explains that operating systems manage each application as a separate task, and when an application initiates an I/O request it creates a thread. Multithreading allows a single process to support multiple concurrent execution paths. Benefits of threads include less overhead for creation, termination, and context switching compared to processes. The document concludes that threads enhance efficiency by sharing resources within a process.
User-level threads (ULTs) are managed by a user-level threads library and do not require a kernel context switch when switching between threads. However, if one ULT blocks, the entire process is blocked. Kernel-level threads (KLTs) are managed by the kernel, allowing true parallelism within a process on multiprocessors. A mode switch is required to switch KLTs but blocking a single KLT does not block the entire process. Threads provide benefits over processes like lower overhead for creation, termination, and context switching.
The document discusses cache coherence in multiprocessor systems. It describes the cache coherence problem that can arise when multiple processors have caches and can access shared memory. It then summarizes two primary hardware solutions: directory protocols which maintain information about which caches hold which memory lines; and snoopy cache protocols where cache controllers monitor bus traffic to maintain coherence without a directory. Finally it mentions a software-based solution relying on compiler analysis and operating system support.
The document discusses processes and threads. A process is an executing program with resources, while a thread is a sequence of execution within a process that shares its resources. Threads have lower overhead than processes and allow for multitasking. However, multithreaded programs are more difficult to debug. Thread management can be done at the user level or kernel level. Different models map user threads to kernel threads, such as many-to-one, one-to-one, and many-to-many.
This document discusses threads and threading models. It defines a thread as the basic unit of CPU utilization consisting of a program counter, stack, and registers. Threads allow for simultaneous execution of tasks within the same process by switching between threads rapidly. There are three main threading models: many-to-one maps many user threads to one kernel thread; one-to-one maps each user thread to its own kernel thread; many-to-many maps user threads to kernel threads in a variable manner. Popular thread libraries include POSIX pthreads and Win32 threads.
Processes and threads are fundamental concepts in Windows Vista. A process contains the virtual address space, threads, and resources for program execution. Each process has a process environment block (PEB) and can create multiple threads, each with their own thread environment block (TEB). Threads are the unit of CPU scheduling and each process must have at least one thread. Interprocess communication (IPC) allows processes to communicate and share data using various methods like pipes, mailslots, sockets, and shared memory. Synchronization objects like mutexes, events, and semaphores coordinate access to shared resources between threads.
Multithreading allows exploiting thread-level parallelism (TLP) to improve processor utilization. There are several categories of multithreading:
- Superscalar simultaneous multithreading interleaves instructions from multiple threads within a single out-of-order processor core to reduce idle resources.
- Coarse-grained multithreading switches between threads on long-latency events like cache misses to hide latency.
- Fine-grained multithreading interleaves threads at a finer instruction granularity in in-order cores.
- Multiprocessing physically separates threads onto multiple processor cores.
The document discusses processes, threads, and multithreading in operating systems. It defines processes as having virtual address spaces and execution paths, while threads are the unit of dispatching. Multithreading allows multiple concurrent execution paths within a single process. Early systems only supported single threading, while modern systems support multiple processes and threads. Threads share resources within a process and have execution states. User-level threads are managed by applications while kernel-level threads are scheduled by the kernel. Symmetric multiprocessing allows threads to execute in parallel on multiple processors.
The CNBS server is a backup solution that can perform both selective online backups of workstations and servers, as well as bare metal restores of offline systems based on various operating systems like Linux, Windows, MacOS, and BSD. It supports backing up multiple filesystems, only saving used blocks to increase efficiency. Almost all steps can be done via commands and options, and it supports features like multicast, mass cloning, and automatic changing of hostnames and SIDs for Windows clients. However, it has some limitations like not supporting differential or incremental backups for offline backups, requiring equal or larger disks for restores, and potential network issues corrupting backups.
Cache coherence is a technique used in multiprocessing systems to maintain consistency between caches and shared memory. When a processor modifies a variable in its cache that is also stored in another processor's cache, inconsistency arises. There are three main techniques to maintain cache coherence: snoopy-based protocols invalidate or update other caches when a write is observed; directory-based protocols use a directory to control access to shared data and update or invalidate caches; and snarfing-based protocols allow caches to watch addresses and data to update copies when writes are seen. Cache coherence aims to ensure data consistency across caches for shared resources.
The document discusses multiprocessor and multicore systems. It defines multiprocessors as systems with two or more CPUs sharing full access to common RAM. It describes different hardware architectures for multiprocessors like bus-based, UMA, and NUMA systems. It discusses cache coherence protocols and issues like false sharing. It also covers scheduling and synchronization challenges in multiprocessor systems like load balancing, task assignment, and avoiding priority inversions.
The document discusses the Linux kernel and its structure. The Linux kernel acts as the interface between hardware and software, contains device drivers for peripherals, handles resource allocation and tracking application access to files. It is also responsible for security and access controls for users. The kernel version numbers use even numbers to indicate stable releases.
Linux memory management uses a combination of physical memory, virtual memory, and paging. It uses a buddy system to allocate and free physical memory pages. Each Linux process gets 3GB of virtual address space, with the remaining 1GB reserved for page tables and kernel data. Linux uses demand paging and maintains lists of frequently and infrequently used pages. It employs a clock replacement algorithm and uses both local and global page replacement policies.
This document compares three distributed operating systems: Amoeba, Mach, and Chorus. Amoeba was designed for distributed systems and uses a pool processor execution model, automatic load balancing, and automatic file replication. Mach was designed for single CPU/multiprocessors and provides extensive multiprocessor support. Chorus is a microkernel-based real-time operating system that is optimized for the local case and provides asynchronous communication. The document outlines key differences between the three operating systems in areas such as architecture, communication methods, memory management, and UNIX compatibility.
The document discusses multiple processor organizations including:
- SISD (single instruction, single data stream) using a single processor.
- SIMD (single instruction, multiple data stream) using multiple processors executing the same instruction on different data simultaneously.
- MISD (multiple instruction, single data stream) transmitting data to multiple processors each executing different instructions.
- MIMD (multiple instruction, multiple data stream) using a set of processors executing different instruction sequences on different data sets like SMPs, clusters and NUMA systems.
Scheduler Activations - Effective Kernel Support for the User-Level Managemen...Kasun Gajasinghe
Presentation slides presented by Kasun Gajasinghe and Nisansa de Silva at Dept. of Computer Science & Engineering, University of Moratuwa. Slides are for the paper titled “Scheduler Activations - Effective Kernel Support for the User-Level Management of Parallelism” by Thomas E. Anderson et.al.
The document provides an overview of operating systems, including what constitutes an OS (kernel, system programs, application programs), storage device hierarchy, system calls, process creation and states, process scheduling, inter-process communication methods like shared memory and pipes, synchronization techniques like mutexes and semaphores, readers-writers problem, and potential for deadlocks. Key concepts covered include kernel mode vs user mode, process control blocks, context switching, preemption, and requirements for deadlock situations.
Application Performance & Flexibility on Exokernel Systems paper reviewVimukthi Wickramasinghe
This document provides an overview of operating system structures and summarizes a research paper discussing the performance of exokernel systems. It introduces layered and alternative OS structures like microkernels and exokernels. The paper discusses the principles of exokernels and evaluates the performance of the Xok exokernel and its components like the XN storage system. Performance tests show Xok can match or exceed UNIX performance for most applications and significantly outperform UNIX for I/O intensive servers like HTTP servers. While exokernels provide advantages like flexibility and performance, their interfaces can be complex and lead to code management issues.
Chorus - Distributed Operating System [ case study ]Akhil Nadh PC
ChorusOS is a microkernel real-time operating system designed as a message-based computational model. ChorusOS started as the Chorus distributed real-time operating system research project at Institut National de Recherche en Informatique et Automatique (INRIA) in France in 1979. During the 1980s, Chorus was one of two earliest microkernels (the other being Mach) and was developed commercially by Chorus Systèmes. Over time, development effort shifted away from distribution aspects to real-time for embedded systems.
This document provides an introduction to writing Linux kernel modules and device drivers. It discusses the structure of the Linux kernel, including the system call interface, kernel subsystems, and architecture-dependent code. It also describes kernel modules, the different types of device drivers (character, block, network), and the layered driver model in Linux. Finally, it provides an example of a "Hello World" kernel module to demonstrate the basic structure of a module and compiling it.
This document provides an overview and tutorial on Linux kernel driver development. It discusses key areas of the kernel source tree relevant for drivers, debugging techniques, basic kernel infrastructure like memory allocation and printing messages, implementing character device drivers, and the virtual file system layer. The tutorial also demonstrates how to add a basic "hello world" kernel module and integrate it into the kernel build system.
User-level threads (ULTs) are managed by a user-level threads library and do not require a kernel context switch when switching between threads. However, if one ULT blocks, the entire process is blocked. Kernel-level threads (KLTs) are managed by the kernel, allowing true parallelism within a process on multiprocessors. A mode switch is required to switch KLTs but blocking a single KLT does not block the entire process. Threads provide benefits over processes like lower overhead for creation, termination, and context switching.
The document discusses cache coherence in multiprocessor systems. It describes the cache coherence problem that can arise when multiple processors have caches and can access shared memory. It then summarizes two primary hardware solutions: directory protocols which maintain information about which caches hold which memory lines; and snoopy cache protocols where cache controllers monitor bus traffic to maintain coherence without a directory. Finally it mentions a software-based solution relying on compiler analysis and operating system support.
The document discusses processes and threads. A process is an executing program with resources, while a thread is a sequence of execution within a process that shares its resources. Threads have lower overhead than processes and allow for multitasking. However, multithreaded programs are more difficult to debug. Thread management can be done at the user level or kernel level. Different models map user threads to kernel threads, such as many-to-one, one-to-one, and many-to-many.
This document discusses threads and threading models. It defines a thread as the basic unit of CPU utilization consisting of a program counter, stack, and registers. Threads allow for simultaneous execution of tasks within the same process by switching between threads rapidly. There are three main threading models: many-to-one maps many user threads to one kernel thread; one-to-one maps each user thread to its own kernel thread; many-to-many maps user threads to kernel threads in a variable manner. Popular thread libraries include POSIX pthreads and Win32 threads.
Processes and threads are fundamental concepts in Windows Vista. A process contains the virtual address space, threads, and resources for program execution. Each process has a process environment block (PEB) and can create multiple threads, each with their own thread environment block (TEB). Threads are the unit of CPU scheduling and each process must have at least one thread. Interprocess communication (IPC) allows processes to communicate and share data using various methods like pipes, mailslots, sockets, and shared memory. Synchronization objects like mutexes, events, and semaphores coordinate access to shared resources between threads.
Multithreading allows exploiting thread-level parallelism (TLP) to improve processor utilization. There are several categories of multithreading:
- Superscalar simultaneous multithreading interleaves instructions from multiple threads within a single out-of-order processor core to reduce idle resources.
- Coarse-grained multithreading switches between threads on long-latency events like cache misses to hide latency.
- Fine-grained multithreading interleaves threads at a finer instruction granularity in in-order cores.
- Multiprocessing physically separates threads onto multiple processor cores.
The document discusses processes, threads, and multithreading in operating systems. It defines processes as having virtual address spaces and execution paths, while threads are the unit of dispatching. Multithreading allows multiple concurrent execution paths within a single process. Early systems only supported single threading, while modern systems support multiple processes and threads. Threads share resources within a process and have execution states. User-level threads are managed by applications while kernel-level threads are scheduled by the kernel. Symmetric multiprocessing allows threads to execute in parallel on multiple processors.
The CNBS server is a backup solution that can perform both selective online backups of workstations and servers, as well as bare metal restores of offline systems based on various operating systems like Linux, Windows, MacOS, and BSD. It supports backing up multiple filesystems, only saving used blocks to increase efficiency. Almost all steps can be done via commands and options, and it supports features like multicast, mass cloning, and automatic changing of hostnames and SIDs for Windows clients. However, it has some limitations like not supporting differential or incremental backups for offline backups, requiring equal or larger disks for restores, and potential network issues corrupting backups.
Cache coherence is a technique used in multiprocessing systems to maintain consistency between caches and shared memory. When a processor modifies a variable in its cache that is also stored in another processor's cache, inconsistency arises. There are three main techniques to maintain cache coherence: snoopy-based protocols invalidate or update other caches when a write is observed; directory-based protocols use a directory to control access to shared data and update or invalidate caches; and snarfing-based protocols allow caches to watch addresses and data to update copies when writes are seen. Cache coherence aims to ensure data consistency across caches for shared resources.
The document discusses multiprocessor and multicore systems. It defines multiprocessors as systems with two or more CPUs sharing full access to common RAM. It describes different hardware architectures for multiprocessors like bus-based, UMA, and NUMA systems. It discusses cache coherence protocols and issues like false sharing. It also covers scheduling and synchronization challenges in multiprocessor systems like load balancing, task assignment, and avoiding priority inversions.
The document discusses the Linux kernel and its structure. The Linux kernel acts as the interface between hardware and software, contains device drivers for peripherals, handles resource allocation and tracking application access to files. It is also responsible for security and access controls for users. The kernel version numbers use even numbers to indicate stable releases.
Linux memory management uses a combination of physical memory, virtual memory, and paging. It uses a buddy system to allocate and free physical memory pages. Each Linux process gets 3GB of virtual address space, with the remaining 1GB reserved for page tables and kernel data. Linux uses demand paging and maintains lists of frequently and infrequently used pages. It employs a clock replacement algorithm and uses both local and global page replacement policies.
This document compares three distributed operating systems: Amoeba, Mach, and Chorus. Amoeba was designed for distributed systems and uses a pool processor execution model, automatic load balancing, and automatic file replication. Mach was designed for single CPU/multiprocessors and provides extensive multiprocessor support. Chorus is a microkernel-based real-time operating system that is optimized for the local case and provides asynchronous communication. The document outlines key differences between the three operating systems in areas such as architecture, communication methods, memory management, and UNIX compatibility.
The document discusses multiple processor organizations including:
- SISD (single instruction, single data stream) using a single processor.
- SIMD (single instruction, multiple data stream) using multiple processors executing the same instruction on different data simultaneously.
- MISD (multiple instruction, single data stream) transmitting data to multiple processors each executing different instructions.
- MIMD (multiple instruction, multiple data stream) using a set of processors executing different instruction sequences on different data sets like SMPs, clusters and NUMA systems.
Scheduler Activations - Effective Kernel Support for the User-Level Managemen...Kasun Gajasinghe
Presentation slides presented by Kasun Gajasinghe and Nisansa de Silva at Dept. of Computer Science & Engineering, University of Moratuwa. Slides are for the paper titled “Scheduler Activations - Effective Kernel Support for the User-Level Management of Parallelism” by Thomas E. Anderson et.al.
The document provides an overview of operating systems, including what constitutes an OS (kernel, system programs, application programs), storage device hierarchy, system calls, process creation and states, process scheduling, inter-process communication methods like shared memory and pipes, synchronization techniques like mutexes and semaphores, readers-writers problem, and potential for deadlocks. Key concepts covered include kernel mode vs user mode, process control blocks, context switching, preemption, and requirements for deadlock situations.
Application Performance & Flexibility on Exokernel Systems paper reviewVimukthi Wickramasinghe
This document provides an overview of operating system structures and summarizes a research paper discussing the performance of exokernel systems. It introduces layered and alternative OS structures like microkernels and exokernels. The paper discusses the principles of exokernels and evaluates the performance of the Xok exokernel and its components like the XN storage system. Performance tests show Xok can match or exceed UNIX performance for most applications and significantly outperform UNIX for I/O intensive servers like HTTP servers. While exokernels provide advantages like flexibility and performance, their interfaces can be complex and lead to code management issues.
Chorus - Distributed Operating System [ case study ]Akhil Nadh PC
ChorusOS is a microkernel real-time operating system designed as a message-based computational model. ChorusOS started as the Chorus distributed real-time operating system research project at Institut National de Recherche en Informatique et Automatique (INRIA) in France in 1979. During the 1980s, Chorus was one of two earliest microkernels (the other being Mach) and was developed commercially by Chorus Systèmes. Over time, development effort shifted away from distribution aspects to real-time for embedded systems.
This document provides an introduction to writing Linux kernel modules and device drivers. It discusses the structure of the Linux kernel, including the system call interface, kernel subsystems, and architecture-dependent code. It also describes kernel modules, the different types of device drivers (character, block, network), and the layered driver model in Linux. Finally, it provides an example of a "Hello World" kernel module to demonstrate the basic structure of a module and compiling it.
This document provides an overview and tutorial on Linux kernel driver development. It discusses key areas of the kernel source tree relevant for drivers, debugging techniques, basic kernel infrastructure like memory allocation and printing messages, implementing character device drivers, and the virtual file system layer. The tutorial also demonstrates how to add a basic "hello world" kernel module and integrate it into the kernel build system.
This document discusses kernel modules in Linux. It begins by defining the kernel as the central part of the operating system that manages processes, memory, devices, and storage. Kernel modules allow new functionality to be added to the kernel at runtime without rebooting. Common module commands like insmod, lsmod and rmmod are described. The document outlines how modules are loaded and unloaded by the kernel and provides a simple "hello world" example of a kernel module.
The document provides an overview of device driver development in Linux, including character device drivers. It discusses topics such as device driver types, kernel subsystems, compiling and loading kernel modules, the __init and __exit macros, character device registration, and issues around reference counting when removing modules. It also provides sample code for a basic character device driver that prints information to the kernel log.
DUSK - Develop at Userland Install into KernelAlexey Smirnov
DUSK is a framework that allows kernel modules to be developed at the user level by compiling them into a user-level program while still maintaining the performance of running in the kernel. It uses helper functions to connect the user-level component to the kernel-level component, allowing things like debugging and testing to be done at the user level. DUSK supports Netfilter modules initially and aims to provide an easier development process for kernel modules.
This document describes how to exploit vulnerabilities in the Linux kernel to perform privilege escalation via a USB drive. It explains how thumbnail generation for DVI files can be exploited to execute arbitrary code with root privileges. The exploit abuses failures to reset address limits during kernel crashes as well as vulnerabilities in the Econet network protocol. By overwriting function pointers, copying an escalation function to memory, and triggering crashes, the exploit gains root access to the system. Potential fixes are also discussed.
unixlinux - kernelexplain yield in user spaceexplain yield in k.pdfPRATIKSINHA7304
this is java. problem.
i already make employee class. but i can not make employeetester class. i want to know
Employeetester class.
EmployeeTester class:
Write a main method that produces a dialog like this:
-->Enter a name : dave
-->Enter hours worked (7 values separated by spaces): 5 2 1 0 0 3 3
Output: dave worked for 5 day(s) for a total of 14.0 hours.
-->Enter a day of the week (0-6): 2
Output: Hours worked on day 2 is 1.0
************and this is my employee class.**********************
public class Employee {
private double[] hours=new double[7];
private String name;
public Employee(String name){
this.name=name;
}
public double getHours(int day){
return hours[day];
}
public void setHours(int day,double hrs){
hours[day]=hrs;
}
public int numDaysWorked(){
int totalD=0;
for(int i=0;i<7;i++){
if(hours[i]==0.0){
}else{
totalD=totalD+1;
}
}
return totalD;
}
public double totalHours(){
double totalH=0;
for(int i=0;i<7;i++){
if(hours[i]==0.0){
}else{
totalH=totalH+hours[i];
}
}
return totalH;
}
public String toString(){
return name+\" Worked \" +numDaysWorked() + \" day(s) for a total of \"+totalHours() +
\"hours\ .\";
}
}
Solution
Note:
I have made some changes to the Employee class which have provided to meet the required
output.Thank You.
________________________
Employee.java
public class Employee {
//Creating an double type array of size 7
private double[] hours=new double[7];
//Declaring variable
private String name;
//Parameterized constructor
public Employee(double[] hours, String name) {
super();
this.hours = hours;
this.name = name;
}
//Setters and getters
public double[] getHours() {
return hours;
}
public void setHours(double[] hours) {
this.hours = hours;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
//This method will calculate the no of days worked by an employee
public int numDaysWorked(){
int totalD=0;
for(int i=0;i<7;i++){
if(hours[i]!=0.0){
totalD=totalD+1;
}
}
return totalD;
}
//This method will return the total no of hours worked by an employee
public double totalHours(){
double totalH=0;
for(int i=0;i<7;i++){
//Calculating the total hours worked
totalH=totalH+hours[i];
}
return totalH;
}
//this method will return the hours worked on particular day of an employee
public double hoursWorkedOnParticularday(int day)
{
return hours[day];
}
//this method will display the contents of an object inside it
public String toString(){
return name+\" Worked \" +numDaysWorked() + \" day(s) for a total of \"+totalHours() + \"
hours\ .\";
}
}
____________________
EmployeeTester.java
import java.util.Scanner;
public class EmployeeTester {
public static void main(String[] args) {
//Declaring variables
String name;
double tot_hours=0;
int no_of_days_worked=0;
int week_day=0;
//Scanner object is used to get the inputs entered by the user
Scanner sc=new Scanner(System.in);
//Creating an double type array of size 7
double hours[]=new double[7];
//getting the name of an employee entered by the us.
This document provides release notes and supplementary information for Delphi 7. It notes that some components have been deprecated and recommends newer alternatives. It also describes changes made to string handling functions, warnings added by the compiler, and issues fixed in streaming of subcomponents. Finally, it provides notes on various other topics like Apache, UDDI, Windows XP input, and databases.
Unit 6 Operating System TEIT Savitribai Phule Pune University by Tushar B KuteTushar B Kute
Recent And Future Trends In Os
Linux Kernel Module Programming, Embedded Operating Systems: Characteristics of Embedded Systems, Embedded Linux, and Application specific OS. Basic services of NACH Operating System.
Introduction to Service Oriented Operating System (SOOS), Introduction to Ubuntu EDGE OS.
Designed By : Tushar B Kute (http://tusharkute.com)
In Apache Cassandra Lunch #41: Apache Cassandra Lunch #41: Cassandra on Kubernetes - Docker/Kubernetes/Helm Part 1, we discuss Cassandra on Kubernetes and give an introduction to Docker, Kubernetes, and Helm.
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Real-World Docker: 10 Things We've Learned RightScale
Docker has taken the world of software by storm, offering the promise of a portable way to build and ship software - including software running in the cloud. The RightScale development team has been diving into Docker for several projects, and we'll share our lessons learned on using Docker for our cloud-based applications.
This document discusses kernel modules in FreeBSD. It explains that some modules need to be compiled into the kernel, while others can be loaded dynamically at runtime. It provides instructions for compiling a custom kernel configuration and installing the new kernel. It also describes how to build and load kernel loadable modules (KLDs) dynamically using kldload and kldstat commands. The key steps for creating a basic kernel module are outlined, including using the bsd.kmod.mk makefile and declaring the module with events for load and unload.
This presentation gives introduction to kernel module programming with sample kernel module.
It helps to start with kernel programming and how it can be used to develop various types of device drivers.
The document discusses processes and threads in an operating system. It defines a process as a program in execution that includes the program code, data, and process control block. A thread is the basic unit of execution within a process and includes the program counter, registers, and stack. The document outlines different process states like creation, termination, and suspension. It also describes different types of threads like user-level and kernel-level threads. Symmetric multiprocessing uses multiple identical processors that can run different threads simultaneously, improving performance. A microkernel is a small OS core that provides message passing between components like the file system or process servers through inter-process communication.
This document introduces debugging ASP.NET applications with WinDBG and dump analysis. It discusses collecting dump files from ASP.NET processes using tools like ADPlus and Debug Diagnostic Tool. It then explains analyzing these dumps in WinDBG using commands and extensions like SOS and PSSCOR2 to diagnose issues like crashes, slow performance, hangs and memory leaks. The document provides an overview of common debugging scenarios, techniques and commands to get started with debugging ASP.NET applications offline using memory dumps.
This document provides an overview of walking around the Linux kernel. It begins with a brief history of Linux starting with Richard Stallman founding GNU in 1984. It then discusses why an operating system is needed and what a kernel is. The document outlines the basic facilities a kernel provides including process management, memory management, and device management. It describes different kernel design approaches such as monolithic kernels, microkernels, and hybrid kernels. Finally, it provides some tips for hacking the Linux kernel such as installing development packages, configuring and compiling the kernel, checking hardware, and loading modules.
Linux device drivers can be loaded as modules at runtime. A module begins with a module_init() function and ends with a module_exit() function. Modules export symbols and functions to be used by other modules. The Makefile is used to compile the module and modprobe loads dependent modules by examining the modules.dep file.
1. The document discusses object-oriented programming concepts like abstraction, encapsulation, inheritance, polymorphism, and dynamic binding.
2. It then provides details on the history and features of Java, including how Java code is compiled and run on the Java Virtual Machine.
3. Core object-oriented features of Java like classes, objects, constructors, and method overloading are explained.
Some basic knowledges required for beginners in writing linux kernel module - with a description of linux source tree, so that the idea of where and how develops. The working of insmod and rmmod commands are described also.
Similar to Linux Device Driver v3 [Chapter 2] (20)
Building a Raspberry Pi Robot with Dot NET 8, Blazor and SignalRPeter Gallagher
In this session delivered at NDC Oslo 2024, I talk about how you can control a 3D printed Robot Arm with a Raspberry Pi, .NET 8, Blazor and SignalR.
I also show how you can use a Unity app on an Meta Quest 3 to control the arm VR too.
You can find the GitHub repo and workshop instructions here;
https://bit.ly/dotnetrobotgithub
3. Outline : Kernel Module
➔ A hello_world program for kernel (source code available in folder).
➔ insmod and rmmod for load unload kernel.
➔ Segmentation fault kills process.
➔ Modules runs in kernel space and application in user space.
➔ Each space has their own memory mapping and address space.
➔ Processor protects from unauthorized access through protection levels.
➔ Kernel is executed under highest level ie. supervisor mode.
➔ For a system call UNIX transfers execution from user to kernel space
4. Outline : Kernel Module
➔ Written in a way to maintain concurrent action can happen.
➔ Kernel codes must be reentrant - Running in multiple context in same time.
➔ Avoid race condition in data structure which might have shared data.
Current process -
➔ current is not truly global variable. For supporting SMP developer developed
this to find current process in relevant processor.
➔ The pointer refers to struct task_struct which refers process currently
executing.
5. Outline : Kernel Module
➔ Smaller stack size, as small as 4096 byte.
➔ DO NOT allocate large auto variable, instead use dynamic memory allocation.
➔ Functions with __ as start of name must be handled with care as these are
low level interface.
➔ No floating point arithmetic as it needs to save floating point state in
processor at each entry and exit. So extra overhead.
➔ modprobe searches for other symbols from any other modules and loads,
whereas insmod may fail with unresolved symbols.
➔ lsmod reads /proc/modules to list loaded modules.
➔ sysfs /sys/module shows same (both virtual filesystem).
6. Outline : Kernel Module
➔ Module build steps has version verification by linking vermagic.o with
module. If things doesn’t match, module won’t be loaded.
➔ /var/log/messages shows problem logs.
➔ To build kernel for multiple version, use macros.ie.LINUX_VERSION_CODE,
KERNEL_VERSION(major,minor,release).
➔ Deal incompatibilities with specific header file.
➔ Kernel symbol table contains global symbol and functions.
➔ Driver module exports symbol to table for other modules to benefit (Module
Stacking).
7. Outline : Kernel Module
➔ Initialization functions are declared as static as it should not be visible
outside specific file.
➔ Module can register many facilities and each facility a specific kernel function
accomplish the registration.
➔ Arguments passed to registration functions is pointer that points to data
structure containing details of facility.
➔ Cleanup function is declared as void as it has nothing to return.
8. Module : Error Handling
➔ For an error a module must perform an undo of all the things that it did before
failure. Linux doesn’t save these activities hence a module must implement
this.
➔ goto is used for error handling. For complex situations, run cleanup function
from within initialization function.
➔ Must check of status of each item before unregistering and clean-up function
can not have __exit when called from non-exit function.
➔ Module load race - Module must complete all supporting initialization before
enabling all facilities.
9. Module Parameter
➔ Parameter can be taken in load time by insmod or from /etc/modprobe.conf
by modprobe
➔ Parameters are declared with the module_param macro, defined in
moduleparam.h.
➔ Macros are placed outside function and found near the head of source file.
➔ All module params should be given a default value.
➔ User-space driver can be implemented although it has pros and cons.